1. Field of the Invention
The field of the invention relates to optical transceivers, and in particular to the actuator and latching mechanism for a pluggable assembly or module that provides a communications interface between a computer or communications unit having an electrical input/output connector or interface and an optical fiber, such as used in fiber optic communication links.
2. Description of the Related Art
A variety of optical transceivers are known in the art which include an optical transmit portion that converts an electrical signal into a modulated light beam that is coupled to an optical fiber, and a receive portion that receives an optical signal from an optical fiber and converts it into an electrical signal. Traditionally, an optical receive portion includes an optical assembly to focus or direct the light from the optical fiber onto a photodector, which, in turn, is connected to an amplifier/limiter circuit on a circuit board. The optical transmit portion contains a photodiode and similar optical provisions and, in turn, is coupled to a driver board.
The photodetector or photodiode is typically packaged in a hermetically-sealed package in order to protect it from harsh environmental conditions. The photodetectors or photodiodes are semiconductor chips that are typically a few hundred microns to a couple of millimeters wide and 100-500 microns thick. The package in which a photodetector or photodiode is mounted is typically 3 to 6 mm in diameter and 2 to 5 mm tall, and has several electrical leads coming out of the package which are, in turn, soldered to the circuit board containing the amplifier/limiter or driver.
Optical transceivers are packaged in a number of standard form factors. Standard form factors provide standardized dimensions and input/output interfaces that allow devices from different manufacturers to be used interchangeably.
Although latching mechanisms for large conventional pluggable modules have been used successfully in the past, they tend to be unsuitable for miniaturization which is an ever-constant objective in the industry. It is desirable to miniaturize transceivers in order to increase the port density associated with the network connection, such as, for example, switch boxes, cabling patch panels, wiring closets, and computer I/O. The SFP MSA standard (i.e., “small form factor pluggable”) has been promulgated, and this standard specifies a predetermined enclosure height and width and electrical input/output connections, and a certain latch design. However, the MSA does not specify any actuating mechanism, which is left to each vendor to implement.
In addition to miniaturizing the module, it is also desirable to increase its operating frequency. For example, applications are quickly moving from the sub-gigabit realm to well over a gigabit. Conventional pluggable module configurations, however, cannot meet these parameters.
Miniaturizing a module, providing a suitable latch actuating mechanism and providing high operating speed, presents a number of design problems, particularly in applications in which data transmission rates are high, e.g., in the range of 1-10 Gbs (Gigabits/second). Of particular concern is providing an appropriate latching actuator while reducing electromagnetic inference (EMI) emissions.